Coherent radiation device irradiated by means of radar waves



4554510 Au 233 Ex l Flpslo XR 3,453,556WV /s'wf/C f Q www g i g t i July1,1959 SZPUR' M a,453,556'

CCB'aP-EN'I RADIATION DEVICE IRRADIATED BY MEANS OF RADAR 'NAVES-sUBsTeTUTE ma mzssxNGXRFil 0- 'fi-196" I una 3453556 0R m sax/ 94.51;

3,453,556 Patented July 1, 1959 United States Patent hice i FIG. l is apreferred embodiment of the laser weapon 3,453.556 embodying theinvention; and

comkf? FIG. 2 is a modification of the device shown in FIG. l.

Referring now to FIG. l, the reference numeral Romletstggfosdggh 5generally indicates a laser weapon according to the in- Fnd ont.6,1'954senNn02041- vention which comprises a typical reectgrgwand a Int-Cl. H015 3/09, 3/22 circular wave guide 14 of any chv`enient designdisposed US. Cl. S31-94.5 3 Claims in'fi'nf'of the reflecting surface ofreflector 12. Wave guide 14 is adapted for connection to n cts-workingradar ABSTRACT OF THE DISCLOSURE Electromagnetic wave energy from aradar transmitter produces an ionization plasma in a rare earth gasstir-A rounding a laser rod, the plasma optically pumps the laser rod toestablish the laser emission.

the radar system in the course of discharging its particular functionare abstracted by wave guide 14. Radiation energy emerging from waveguide 14 follows the path of the "arrows shown thus being reflected fromreector 12 and 15 'then being applied to a housing 16 generally tubularin cross section and lying between reflector 12 and wave guide 14. Thelocation of housing 16 within reector The invention described herein maybe manufactured gdiiftgiorggggd sind Pam 0f ogufggstwligg tgsaycxnrc;f2; 20 Inwardly extending end walls 17 and 18 in housing 3,, royaltythereon 16 fxedly restrain a rod or bar 20 of active laser mate- 'rhiscase rclates'to cohnrem radiation devs and rial in concentric relationto the axis of rellector 12. particularly, to a laser weapon in -whichradar waves agsshigby s appl-opnam 2 gam "he :cttpgng iarnffnp End faces22 and 24 ofrod 20 are suitably covered Laser dew-ces mow-n in thc angenerallv cmplgv as with a reflective coating 26 which enhances internalre- ,f'-y the chief clement a rod or bar of active material vigorouslygggbfeoogcg" zegldoffagzhz productive, when excited by copious amountsof visible light, of monochromac coherent radiation extensive in 3orellective whereas end face 24iscoated to produce roughly penetratingand destructive power. Major problems in the -production of coherentradiation for use in military applii cations include the nonexistence ofa light-weight, nioder. ately priced, and relativelysimplc technique foradequately alg :razz 2521511625 formed with a ,cylin- 21325ghrntgdltsnnlngrgwm: sxaennfoxL-lg 35 drical transparent glass envelope28 for admitting the i non bcncial to sonnent emission has procrw, alongelectromagnetic radiation incident on reflector 12. Rod 20 miscellaneouslines one successful method beit-ing^ to disis slced partially over inkngih by a Elgar capsule 30 charge a capacnor bank through ons or moreashlamps similarly transparent to the radiation entering envelope 28. idisposed to bathe the laser crystal in intense light, This o The capsule30 contains an ionizable rare earth gas such as t method, however,proven somewhat costly due to fnonsy'hclg'hvlnangdush luumme thenecessary acquisition and storage of the capacitive SPH mg g y say, 2percent. Coherent radiation emerges through end face 24 where theborestrcam passes unitindered through a 10 system (not shown) by whichradar waves emitted by 98 percent reectivity, leaving a transmissionfigure of,

elements.

optical laser pumping.

Accordingly, one obiect of this invention is to provide a laser weaponwhich relies on an external and separately operating installation tosupply the energy essential for plasma column, as known in the art, willoptically pump rod 20 from virtually all directions and establish thecol Anothcr obje? of thneuminon -the pmmwn of circulated under pressurethrough the interior of housing arrll'iegy" um y g mamy wmpam 16 to acoolant entre: s4 n the other end. The irrigation Yet nnntnnn bj-nd oftnn nventinn is to gravide a 5 ofthe rod 20 ard capsule 30 dissipatesthe heat developed laser weapon versatile in the respect that radarwaves dwing Citation 0f the Pumping energy source and is issuing fromany satisfacwly powerful radar system explained by the flow lines 35shown. Moreover, the can comm-nnte the necessary primary excitationcoolant establishes a fairly constant operating temperature To -ny theforegoing einem into :geen tn'e coherent thereby giving better and morelasting use of the laser n 0 55 material. The rapid cooling of thehousing 16 after each radiation weapon embodying the inventioncapitalizes on injection of pumping energy is also conducive to com vthe pr-esen 0f dat waws from zo-working apparatus sistent production ofoptical light which has a wavelength and dwerg time' -waves momcmaryfmmdie purpose matchin the ab tion band of rod 20 Further adviin` theyserve tor excittngaplasmagenerat ing medium where- :s org thc cxslnedheat reduconinclude wat bythe energy o f the laser material is raisedtothe coherent g mp. P d l r reservation of the cu-veradiation-initiating level. Periodic abstractions on the order Egg anngc p of several microseconds each are enough to stimulate the l Plasmao :mit optical umg), at the conca emission Any suitable means, notshown, ma) be used for mount in .the various elements hereinabovedescribed in the spectrum. Such parasitic accretion is easily achievedwith dgn. positions with Sm to eh other. For example,

"nodebllity of the host system on which it depends. '65 ma 12 may bgmounted on the hull, airframe, or A complete understanding of theinvention and n nbuitheaa of the vehicle from which power admittedtroduction to other objects not specifically mentioned may ihmugh waveguide 14 will be drawn. be had from the following description of theinvention Referring now to FIG. 2. a secondary reector 36 is when readin coniunction with the accompanying drawings disposed -behind reflector12 for directing coherent radiaseveral views, and wherein: 38 to acollector 40 cf suitable design. The breadth of wherein like referencecharacters refer tc like parts in the 7 tion energy returning fromobjects a'ected by the wave reflector 12 is selected such that reflector36 is protected from high power radiation from wave guide I4. Collector40 thus may be connected to external means which may take the form oftracking, ranging, interrogating, or lirecontrol apparatus not shown.Thus, with very little modication, the principles underlying thepreferred embodiment of FIG. l can conveniently be extended by theaddition of reflector 35 and collector 40 to tforruv a weapon systemeasily integrated into still other apparatus. The arrangement of FIG. 1can. for example, either be stationary or adapted for turret control. Inthe interest of simplicity, the cooling feature as would be applied tothe FIG. 2 embodiment has been omitted. Also, for the details of endmounting rod 20 reference may be had 10 FIG. 1.

In operation, radar waves leaving wave guide 14 are reected fromreflector 12 and enter housing 16 through envelope 2S where they richlyexcite the plasma-producing gas contained in capsule 30. The plasmaduring its generation is selected to have an emitted energy band inresponse to radar wave bombardment which will excite the crystalmaterial in rod 20 at a wavelength most favorable for maximummonochromatic coherent radiation. Coherent light generated in rod 20 istransmitted back toward wave guide 14 and moves unhnmpered therethrough.Simultaneously, the internal temperature of housing 16 is maintained atacceptable levels by means of .the circulating coolant.

Xt will be understood that rather- Vthan using merely a single laserelement as shown in the illustrated embodiments, equally useful is anarrangement which includes van array of several laser elements (notshown) distributed is fed from a. radar gtransmqgi E9 @B external load,a laser weapon comprisingzhbody capable of the emissiom of *coherentradiation and ha `v ing a length several times larger than itscross-'sectional dimension, means for rendering one end of said bodytotally relieclive and the opposite i end partially transparent toafford egress Aof'said coherent radiation from said opposite end. anencapsulated ionizable vplasma-producing gas confined about said bodyover part of its length for optically pumping said body to obtain 4coherent emission radiation, a transparent envelope covering said gasand said rod with a space therebetween for fluid circulation, meanshaving inlet and exhaust conncc tions with said envelope for circulatinga heat-absorption agent through said envelope, a reflector disposedbehind said body facing said totally reflective end and disposed inenergy-focusing relation with said ionizable means, and waveguide meansaligned facing said reflector and said partially transparent end of saidbody but removed from the borestream of said coherent radiation forabstracting from said transmitter a portion of its transmission energythereby permitting irradiation of said ionizable means followingimpingement of said retiector. 2. Apparatus according to claim 1 furthercomprising a secondary reector disposed behind sait. `rst-named re'ector and being of predetermined size to avoid being shadowed by saidrst-named reector, said secondary reflector being disposed to collectecho signals from objects affected by said coherent radiation.

3. A laser system comprising: j

(a) ruby laser rod means capable of. being optically pumped and having arehearing end and a laser radiation emitting end, for providing aborestream of laser emission;

(b) capsule means positioned in sleeve relationship with the said laserrod containing xenon gas;

(c) circular radar waveguide means concentric with the said borestreamand having a central aperture for the passage of said borestream, fordirecting radar electromagnetic wavt` radiation energy in the generaldirection of the said laser rod; and

(d) reecting means spaced apart from the said reliecting end of thelaser rod, ,cooperating with the said waveguide means for reflecting thesaid radar electromagnetic wave radiation from the said waveguide ontothe xenon gas for ionizing the xenon gas to provide a gas plasma foroptically pumping the said ruby laser rod.

References Cited vUNITED STATES PATENTS 3,353,115 1l/1967 Maiman 331-945OTHER REFERENCES Crompton et al., Plasma Pumped Laser, Electronics, Mar.23, 1964, vol. 37, No. l2. l

RONALD L. WIBERT, Primary Examiner.

T. MAJOR, Assistant Examiner.

9/1965 Colgate et al. BSI-#94.5

